The invention relates to a process and a device for measuring the mechanical compaction the depth of an agricultural material as well as a device for carrying out the process.
Agricultural materials, such as, for example, crushed grains of wheat or corn or chopped green materials, may be preserved by compacting and thus reducing the volume of trapped air. This process is employed on a large scale, for example, when chopped corn or grass is placed in horizontal silos for silage. Here, chopped green materials are introduced into a silo in layers and compacted by driving over them with a tractor, a wheeled loader, or a roller. The quality of the conserved fodder and the storage losses are crucially determined by the compacting and the achieving of a minimum storage density.
Employed primarily for research purposes are processes in which special measuring instruments are used to conduct measurements at discrete points and discontinuously. This is possible using radiometric probes, which are inserted at least 20 cm deep into the material. Used in practice are also coring cylinders, by means of which a defined volume of the material is withdrawn and weighed in order to calculate the density. Both processes are so tedious and associated with risks that, as a rule, a measurement of density is dispensed with. Instead, at best a visual evaluation is made on the basis of the penetration depth of the compacting vehicle, although this does not allow a quantitative conclusion.
Known are measuring devices on compacting rollers for creating construction subsurfaces in, for example, road construction, Used here is an acceleration sensor, which is joined to the vibrating roller of the machine. On a subsurface that is defined by a specific composition and has a compaction determined beforehand by measurement technology, the sensor delivers a reference signal, which then serves as set target for the entire area of the same subsurface. This reference value is indicated in various ways to the driver in the cabin of the compacting vehicle. The process has the drawback that the density is not measured directly. Moreover, it may be employed only for vibrating machines having a constant characteristic frequency.
Described in DE 102 36,515 and EP 0 843,959 are measuring devices for determining the constituent substances and/or characteristics of harvested material in an agricultural machine. However, a measurement of the compaction of a subsurface in its depth is not described.
Further described in DE 103 06,725 is a process and a device for determining the parameters of harvested materials by using a compacting device that can be filled with a sample of the harvested material during the working process. In the compacting device, a partial quantity separated from the flow of material is compacted to a specific value in order to rule out the influence of density on the material parameters to be measured. The measurement of the parameters of the harvested material is conducted in a compacting chamber intended for receiving the samples. Here, the creation of a constant density serves as a means of being able to quantify unequivocally other material parameters that depend on the density. The density here is determined from the chamber volume and the weight of the material contained in it and does not involve any detection by measurement technology of the density of a subsurface during traversal thereof.